1) Field of the Invention
The present invention generally relates to a microwave oven having an electric heater for cooking by radiant heat.
2) Description of the Prior Art
A microwave oven is a cooking appliance which cooks food with high speed frequency energy of 2,450 MHz. This energizes food molecules to move at high speeds to produce frictional heat. Such a microwave oven also has a heater in its cooking chamber to provide a grilling function for cooking food using direct heat.
FIG. 1 is a front view of a conventional microwave oven. As shown in FIG. 1, the conventional microwave oven includes a cooking chamber 10 in which food is cooked by high frequency energy; a door 20 for opening and closing the cooking chamber 10; a rotary motor (not illustrated); a rotary stand 11 connected with the rotary motor; and a tray 12 adapted to be positioned on the rotary stand 11, and on which the food is placed.
The conventional microwave oven also includes a heater 13 for performing the grill function; a thermistor 14 which senses the temperature of the cooking chamber 10; a control panel having a display 30 showing the operation information of the microwave oven and a function selection part 40; a magnetron antenna (not illustrated) mounted on the sidewall of the cooking chamber's upper portion for emitting high frequency energy to the cooking chamber 10; and a magnetron (not illustrated) installed in a space at the rear of the display 30 for applying the high frequency energy to the magnetron antenna.
The heater 13 is positioned on the rear upper portion of the cooking chamber 10 and is able to be rotated by a predetermined angle. The heater 13 is held in place by a supporting member each provided on a side wall of the cooking chamber 10. Thus, when a user cooks with the heater 13, a lamp of the cooking chamber 10 (not illustrated) is switched on to illuminate the cooking chamber 10, and the tray 11 then rotates. Heat is produced when electricity is applied to the heater 13. When the programmed cooking time is complete, the electricity applied to the heater 13 is shut off, and the heater 13 stops producing heat. When the cooking operation is complete, the microwave signals the user.
The heater 13 remains hot for a predetermined period of time even after the cooking time has finished, since its temperature diminishes slowly. Since the conventional microwave oven cannot measure the temperature of the heater 13, the user may not know that the temperature of the heater 13 is higher than the microwave oven's internal temperature. Thus, when the user tries to cook food with the conventional microwave oven before the heater 13 cools, he may touch the hot heater 13 as he either puts the food being cooked in the cooking chamber 10 or takes it out of the cooking chamber 10. If his or her hand touches the heater 13, he or she may get burnt, and instantaneously drop the food that he or she is holding.